Rotary brush

ABSTRACT

A ROTARY END BRUSH OR CUP BRUSH IS PROVIDED WITH A DURABLE COLLAR SURROUNDING THE BRISTLES WHERE THEY EMERGE FROM THE BRISTLE HOLDER, THE COLLAR HAVING A SMOOTH CONVEXLY CURVED BRISTLE SUPPORT SURFACE (E.G., AS AN O-RING) FOR SUPPORTING THE BRISTLES WHEN THEY FLARE DURING BRUSH ROTATION, THE BRISTLE SUPPORT SURFACE BEING ELASTOMERIC AND HAVING A HARDNESS IN EXCESS OF ABOUT 50 SHORE A DUROMETER, THE COLLAR BEING REINFORCED AGAINST EXPANSION (E.G., BY LOCATING IT AT LEAST PARTIALLY WITHIN THE BRISTLE HOLDER), AND THE BRISTLE HOLDER BEING CONSTRUCTED OF EITHER METAL OR PLASTIC.

June 22, 1971 Agr, QCHOHELD y 3,585,671

ROTARY BRUSH Filed sept. 27. 196s ARTHUR T. scHoFlELD BY MQW, @wena cJ/aaxell ATTORNEYS vUnited States Patent O 3,585,671 ROTARY BRUSH Arthur T. Schofield, Brecksville, Ohio, assignor to The Manufacturers Brush Company, Cuyahoga County,

Ohio

Filed Sept. 27, 1968, Ser. No. 763,238 Int. Cl. A46b 3/10, 13/02 U.S. Cl. --180 25 Claims ABSTRACT OF THE DISCLOSURE A rotary end brush or cup brush is provided with a durable collar surrounding the bristles where they emerge from the bristle holder; the collar having a smooth convexly curved bristle support surface (e.g., as an O-ring) for supporting the bristles when they flare during brush rotation; the bristle support surface being elastomeric and having a hardness in excess of about 50 Shore A durometer; the collar being reinforced against expansion (e.g., by locating it at least partially within the bristle holder); and the bristle holder being constructed of either metal or plastic.

THE INVENTION This invention relates to rotary brushes and more particularly to end brushes and the like which are suitable for being driven in power machinery.

End brushes or cup brushes are a category of brushes generally characterized by the fact that their bristle material, such as wire bristles for example, extends generally parallel to the axis of rotation of the brush and tends to are radially outwardly when the brush is driven at high speeds in power machinery. An important factor reducing the effective life of these brushes has been their tendency to undergo long bristle fracture i.e., breakage of the bristles at the point where they emerge from the bristle holder. When driven at high speeds, long bristle fracture often renders many of these brushes useless long before the bristles have worm down to unusably short lengths.

In the past, long bristle fracture in end brushes has been reduced by bridling the bristles. In U.S. Pat. 2,325,629 the bristles are bridled with a coiled wire spring. In U.S. Pat. 2,421,647, a removable sleeve is employed. U.S. Pat. 2,989,767 shows a brush having a length of plastic tubing that covers the bristle holder and extends a short distance beyond the rim of the holder to engage the bristles where they emerge from the cup. Another brush has a length of plastic tubing covering the bristle holder and extending a short disance beyond the rim of the holder, with a narrow foam collar inserted beneath the tubing to encircle and engage the bristles where they emerge from the bristle holder.

Devices of the types described above have been of assistance in preventing long bristle fracture. Nevertheless, I believe that with most of these and other similar brushes, a great proportion of bristle wear leading to long bristle fracture occurs at the instant that the rotating brush is lplaced under load (i.e., at the instant when the brush is applied to the workpiece). When, for example, an end brush is driven at high speed (c g., in the range of 8-25,000 r.p.m.) under no load conditions, its bristles flare radially outwardly, bending across either the rim of the bristle holder or across a bridle or collar, if one has been employed. When the brush is then applied to a workpiece, the workpiece exerts a retarding force on the bristles causing the bristles to undergo a momentary angular deflection in a direction opposite to the direction of rotation of the bristle holder during which time they rub against the holder rim or bridle. I believe this rubbing is a significant 3,585,671 Patented June 22., 1971 ICE source of bristle wear leading to long bristle fracture, partly because of the abrasiveness of the holder rim or bridle, and partly because of its tendency to cause the bristles to twist. The bristles undergo a similar deflection as the pressure with which the brush is applied to the workpiece varies, and also when the brush is overloaded (i.e., pressed against the workpiccewith a greater force than the brush is designed to encounter.)

An important advantage of the present invention is that it provides a collar which supports the ared bristles away from the rim of the bristle holder, and that this collar presents a bristle support surface that permits the bristles to slide freely along the collar and is also very durable. Other collars such as have been constructed of foam, for example, may provide a satisfactory cushion for the bristles and also prevent the bristles from bending sharply at the cup rim, but such collars exert an undue drag upon the bristles and, as a result, not only may tend to cause bristle fatigue but are quickly damaged or destroyed by the abrasive rubbing action of the bristles. By employing a special collar in a particular manner according to the present invention, I have provided a highly durable brush. Furthermore, due to the durability of the aforesaid collar in the brush of my invention, it is now feasible for me to construct my brush holder from inexpensive plastic. Absent a protective collar, the bristles tend to cut the rim of a plastic holder and prior attempts to employ other collars in such holders have been unsatisfactory, since such collars wear out much too quickly for the brush to have an effective life comparable to that of brushes with metal holders.

Accordingly, it is a primary object of my invention to provide a novel power driven rotary brush having improved useful brush life.

`It is another object of my invention to provide a novel power driven rotary brush in which the holder may be constructed of a plastic.

It is still a further object of my invention to provide a novel power driven rotary brush having a collar which assists in reducing long bristle fracture.

These and other objects and advantages of the present invention will be apparent to those skilled in the art from the following description, claims and drawings. To the accomplishment of the foregoing and related ends, the invention then comprises the features hereinafter fully described and particularly pointed out in the claims, the following description and annexed drawing setting forth in detail certain illustrative embodiments of the invention, these being indicative however of but a few of the various ways in which the principle of the invention may be employed.

In the annexed drawing:

FIG. 1 is an elevational view of a rnetal cup and brush constructed in accordance with my invention.

FIG. 2 is a transverse section taken on the line 2 2 of FIG. 1.

FIG. 3 is a longitudinal section taken on the line 3 3 of FIG. 1.

FIG. 4 is a transverse section taken on the line 4-4 of FIG. 1.

FIG. 5 is an exploded view of the brush shown in FIG. 1 prior to assembly.

FIG. 6 is an elevational view with a portion shown in section of a plastic cup end brush constructed in accordance with my invention.

FIG. 7 is a transverse section taken on the line 7-7 of FIG. 6.

FIG. 8 is an exploded View of the brush shown in FIG. 6 prior to assembly.

Referring now more particularly to the drawing, FIGS. 1-5 show a rotary end brush 1 having a metal holder 2 with a cup shaped bristle receiving portion 3 and a stem or shank portion 4 extending from the base 7 of the cup 3. The shank 4 is for mounting the brush 1 in an appropriate chuck in power machinery so that the brush 1 may be driven at high speeds e.g., on the order of 8-25,000 r.p.m. The cup shaped portion 3 of the holder 2 has rim 5, side wall 6 and base 7 portions.

One end of a bundle of bristles 8 is disposed in the cup shaped portion 3 of the holder 2, and the other end extends from the cup so that the bristles extend generally in a direction parallel to the axis of the shank. The end of the bristles 8 held in the cup 3 is bound by a metal ring 9, and the bound bristles are held securely in the cup 1 by crimping the cup rim 5 inwardly. Other conventional modes of bristle anchoring may be employed such as by looping the bristles about a ring held in the bottom of the cup, or by setting the bristles in solder.

A toroidal rubber collar 10 encircles the bristles 8 where they emerge from the cup portion 3 of the holder f 2, and is held there by the inwardly crimped cup rim 5.

Rubber rings suitable for use as collars in the brush of the present invention are currently sold for use as sealing rings for valves and the like and are known generally in the trade as O-rings. I prefer to use O-rings for my collars because of their low cost and ready availability in a variety of sizes. Accordingly, I have shown the use of O-rings in the drawings and will refer to O-rings often in the remainder of the description, although it is understood that my invention is not so limited.

The O-ring collar 10 is formed of an elastomeric material, preferably a copolymer of butadiene and acrylonitrile, with a hardness of about 70 Shore A durometer although other elastomeric materials may be employed. The surface of the O-ring 10 is very smooth and its width is on the order of 1/8 so that the portion 11 of the collar 10 that supports the bristles when they flare (hereinafter referred to as the bristle support surface 11) has a radius of curvature of about 1/16". The bristle support surface 11 should have a radius of curvature of not less than about 1/32" or the bristles will undergo relatively sharp ftexing when they flare across the collar and an undue amount of bristle fatigue ensues. A too small radius of curvature also leads to reduced collar life since it results in a smaller bristle support surface and increased bristle pressure on that surface.

It is appreciated in understanding the present invention that when a collar is employed to guard the bristles from the bristle holder, both the shape and composition of the collar are very important to the longevity of the brush. A weak collar (e.g., one that is of too soft material or that has a low abrasion resistance or, even though a proper elastomer be employed, if the collar has sharp edges that are susceptible to being cut by the bristles) may be very effective in temporarily reducing the factors leading to long bristle fracture, but the effectiveness of the collar itself is destroyed too quickly and effective brush life is not improved as much as if the collar remained effective for a longer period. Thus it becomes apparent that a collar must be constructed with a bristle support surface that takes into account not just its effect upon the bristles, but also the effect of the bristles upon it.

I have found that a smooth convexly curved bristle support surface of elastomeric material having a hardness in excess of about 50 Shore A durometer minimizes the deleterious effects which the bristles and the bristle support surface have upon one another. I also have found that a butadiene-acrylonitrile elastomer having a hardness in the range of 50'-90 Shore A durometer (preferably about 70 Shore A durometer) is an ideal material because it is non abrasive and soft enough to cushion the bristles e.g., in the event of brush overloading. On the other hand, it is hard enough to provide sufficient support to permit the bristles to slide freely over the collar and be durable. It is very important that the collar have a smooth bristle support surface. Foamed elastomers, for

4 example, generally have a discontinuous surface which is, as a result, relatively rough by comparison to the smooth surface of a butadiene acrylonitrile O-ring.

It is further important in understanding the present invention to appreciate that the pressure of the bristles against the bristle support surface of the collar tends, not only to compress the collar, but also to cause it to stretch and expand. It is undesirable for the collar to undergo substantial expansion since it is likely to either break or expose the holder to the bristles in regions where the holder and bristles should be protected from one another. As shown in FIG. 3, where I employ an O-ring collar 10, I prefer to prevent unwanted collar expansion by locating at least a portion of the O-ring 10 within the bristle receiving portion 3 of the holder 2 (i.e., below the holder rim 5) so that the holder 2 serves to reinforce the collar 10 against any substantial amount of expansion. Other means to reinforce this and other collars within the scope of the present invention will be readily apparent to persons of ordinary skill.

Referring now to FIGS. 6-8 inclusive, there is shown a rotary end brush 12 constructed in accordance with the principles of the present invention, and having a holder 13 with a .polymeric or plastic cup shaped bristle receiving portion 14. The cup shaped portion 14 has base 15, side wall 16 and rim portions 17. The base 15 of the cup 14 is molded onto a metal shank or stem 18. The metal shank 18 has disc-like anchor fiange 19 over which the plastic cup 14 is molded and that ange 19 is provided with a number of bosses 20 to prevent the shank 18 from twisting in the plastic. The shank 18 is for mounting the brush 12 in the jaws of an appropriate chuck to drive the brush in power machinery at high speeds e.g., on the order of 8-25,000 r.p.m.

One end of a bundle of bristles 21 is bound by a metal ring 22 and disposed in the holder cup 14 and the other end extends from the cup 14 so that the bristles lie generally in a direction parallel to the axis of the shank 18. Epoxy may be employed to cement the Ibristle bundle 21 in the cup and the binding ring 22 and/or the cup 14 may be provided with radially extending flanges (not shown) which t into corresponding slots (not shown) on the opposed surface and act to reinforce the bristle bundle 21 against twisting in the cup 14.

A toroidal rubber collar 23 (preferably an O-ring) having a bristle support surface 24 encircles the bristles 21 where they emerge from the cup portion 14 of the holder 13. Once the bristles and O-ring are assembled in the cup 14, the plastic cup 14 is heated to make it deformable, whereupon its rim 17 is bent inwardly to assist in holding O-ring 23 and bristles 21 in place. Requirements for collar design in plastic cup brushes of the present invention are essentially the same as for the metal cup brushes of the invention.

The polymeric cup 14 is formed from a solid synthetic resin, preferably nylon. Nylon has been chosen, among other reasons, for its good mechanical properties and for its high heat resistance.

The suitability of the brush of the present invention for construction of its cup portion from plastic is an important advantage. The bristle holder having a plastic cup is less expensive and lighter weight than comparable metal holders. It is also attractive and protects the workpiece from accidental contact of the holder with the workpiece during the brushing operation.

The bristles in both metal and plastic cup end brushes of the types 1 and 12 shown in the drawings are of steel wire between about .005" and .020 in diameter and the cup portions of such end brushes have interior diameters between about 1/2" and 1%". The principles of the present invention have applicability, however, to larger cup brushes of the type shown, for example, in U.S. Pat. No. 2,062,047.

It should be noted in considering the use of polymeric materials in construction of brush holders that although the brushes of the present invention have been discussed primarily in terms of polymeric bristle receiving portions, that it is contemplated that the shank or other portions serving to couple the brush to power machinery may also be constructed of polymeric material and may be of unitary construction with the bristle receiving holder portions at a substantial savings in cost, although generally higher cost plastics such as certain glass filled compounds are usually employed to obtain the desired strength.

I claim:

1. An improved rotary brush having a holder with a bristle receiving portion, a stem portion extending from the base of said bristle receiving portion or other means for mounting and driving the brush in power machinery, and a -bundle of bristles with one end of said bundle mounted in said bristle receiving portion and with the other end extending therefrom so that when said brush is driven in rotation about its axis, said bristles tend to are radially outwardly from the axis of rotation of said brush; said improvement comprising a collar encircling said bundle of bristles where they emerge from said holder, said collar having a smooth convexly curved bristle support surface for supporting said bristles when they iiare radially outwardly during brush rotation, said collar being of an elastomeric material with a hardness in excess of about 50 Shore A durometer, and means for reinforcing said collar against substantially expansion during use of said brush in power machinery.

2. An improved rotary brush as recited in claim 1 wherein said collar is an O-ring constructed of elastomeric material having a hardness between about 50 and 90 Shore A durometer.

3. An improved rotary brush as recited in claim 2 wherein the major ingredient of said elastomeric material is a copolymer of butadiene and acrylonitrile.

4. An improved rotary brush as recited in claim 1 wherein the material from which said bristle receiving portion of said holder is constructed consists essentially of a polymer.

5. An improved rotary brush as recited in claim 1 wherein the material from which said bristle receiving portion of said holder is constructed consists essentially of a solid synthetic resin.

6. An improved rotary brush as recited in claim 1 wherein the material from which said bristle receiving portion of said holder is constructed consists essentially of nylon.

7. An improved rotary brush as recited in claim 4 wherein said collar is an O-ring.

8. An improved rotary brush as recited in claim 7 wherein the basic ingredient of said elastomeric material is a copolymer of butadiene and acrylonitrile having a hardness between about 50 and 90 Shore A durometer.

9. An improved rotary brush as recited in claim 8 wherein said polymer consists essentially of nylon.

10. A rotary brush comprising a holder with a cupshaped bristle receiving portion; a stem portion extending from the base of said cup-shaped portion for mounting and driving the brush in power machinery; a bundle of bristles with one end of said bundle mounted in said cupshaped portion and the other end extending from said cup-shaped portion so that when said brush is driven in rotation about the axis of said stem, said bristles tend to ilare radially outwardly from the axis of rotation of said brush; and a collar encircling said bundle of bristles where they emerge from said holder, said collar having a smooth convexly curved bristle support surface for supporting said bristles when they flare radially outwardly during brush rotation, said collar being of an elastomeric material with a hardness in excess of about Shore A durometer, at least a portion of said collar located within said bristle receiving portion of said holder to prevent substantial expansion of said collar during use of said brush in power machinery.

11. A rotary brush as recited in claim 10 wherein said elastomeric material has a hardness between about 50 and 90 Shore A durometer.

12. A rotary brush as recited in claim 10 wherein the basic ingredient of said elastomeric material is a copolymer of butadiene and acrylonitrile.

13. A rotary brush as recited in claim 10 wherein said elastomeric material has a hardness between about and Shore A durometer.

14. A rotary brush as recited in claim 10 wherein the interior diameter of said cup-shaped portion is between about 1/2 and 11/i; and wherein said bristles are of steel wire having a diameter between about .005 and .020.

15. A rotary brush as recited in claim 14 wherein the radius of curvature of said bristley support surface is not less than about /g.

16. A rotary brush as recited in claim 1S wherein said collar is an O-ring constructed of elastomeric material having a hardness between about 50 and 90 Shore A durometer.

17. A rotary brush as recited in claim 16 wherein the major ingredient of said elastomeric material is a copolymer of butadiene and acrylonitrile.

18. A rotary brush as recited in claim 10- wherein the material from which said cup portion of said holder is constructed consists essentially of a polymer.

19. A rotary brush as recited in `claim 10 wherein the material from which said cup portion of said holder is constructed consists essentially of a solid synthetic resin.

20. A rotary brush as recited in claim 10 wherein the material from which said cup portion of said holder is constructed consists essentially of nylon.

21. A rotary brush as recited in claim 18 wherein said elastomeric material has a hardness between about 50 and Shore A durometer.

22. A rotary brush as recited in claim 21 wherein said collar is an O-ring.

23. A rotary brush as recited in claim 22 wherein the basic ingredient of said elastomeric material is a copolymer of butadiene and acrylonitrile having a hardness between about 60 and 80 Shore A durometer.

24. A rotary brush as recited in claim 23 wherein the interior diameter of said cup-shaped portion is between about 1/2 and 1%", wherein said bristles are of steel wire having a diameter between about .005 and .020", and wherein said O-ring has a width between about 1/16 and 1A".

2S. A rotary brush as recited in claim 24 wherein said polymer consists essentially of nylon.

References Cited UNITED STATES PATENTS 2,325,629 8/1943 Peterson 15-180X 2,421,647 6/1947 Peterson 15-180 2,730,753 1/1956 Gerber 15-169X PETER FELDMAN, Primary Examiner 

